The present invention relates generally to a storage, and more particularly to a head apparatus that records information in and reproduces the information from a disc as a recording medium in a disc drive. The present invention is suitable, for example, for a head apparatus in a hard disc drive (“HDD”).
Along with the recent spread of electronic apparatuses, there are increased demands for stably using HDDs in various circumstances, and for providing them less expensively. In the HDD, a head records the information in and reproduces the information from a disc while a slider floats above the disc. As the disc rotates, airflow occurs, which generates a lifting power or buoyancy for floating the slider from the disc plane. On the other hand, the suspension that supports the slider applies an elastic force to the slider against the lifting force. The conventional HDD controls the flying height of the slider by the lifting power through a balance between the lifting power (positive pressure) and the elastic force (load), or by maintaining positive pressure equal to load.
The elastic force is constant, whereas the positive pressure is sensitive to an air state, such as a concentration, a temperature, a humidity, and a viscosity. Consequently, the flying height is likely to be unstable in the conventional structure. When the slider is spaced from the disc with an excessively large flying height, the information cannot be recorded or reproduced. On the other hand, an excessively small flying height causes the slider to collide with the disc, and one or both of them to get damaged or recorded data to be erased due to the collision. Accordingly, it has recently been proposed to provide a negative pressure part to the slider in order to achieve (positive pressure)=(negative pressure)+(load). The negative pressure also depends upon the air state similar to the positive pressure, and its variation amount cancels out the variation amount of the positive pressure. The above scheme is thus advantageous in that the flying height becomes stable without being subject to influence of the air state.
Conventionally, the negative pressure part is arranged adjacent to the positive pressure that defines a pitch angle, because this arrangement can enhance the negative pressure effect and easily create the negative pressure. Therefore, a conventional slider 10 arranges a negative pressure part 16 just after a first positive pressure part via a wall 14, as shown in FIG. 6A, in an airflow direction X from an air inflow end IE to an air outflow end OE. FIG. 6B is a partial sectional view of FIG. 6A. The positive pressure part has an air bearing surface (“ABS”) part 12a that effectuates the positive pressure, and a step part 12b that enhances the effect of the ABS part 12a. The positive pressure part includes a first positive pressure part 12A, a pair of second positive pressure parts 12B, and a third positive pressure part 12C. The first positive pressure part 12A is provided closest to the air inflow end IE, and defines a pitch angle of the slider 10. A pair of second positive pressure parts 12B are provided between the first and third positive pressure parts 12A and 12C, and maintains a right and left balance with respect to the X direction of the slider 10. The third positive pressure part 12C is provided closest to the air outflow end OE (near a head 20), and defines the flying height of the slider 10. The head 20 is provided at the center part close to the air outflow end OE of the slider 10.
Prior art includes, for example, Japanese Patent Applications, Publication Nos. 2000-21111, 2001-93250, and 2001-202732.
The negative pressure part 16 when provided just after the first positive pressure part 12A increases a drop in flying height (simply “drop” hereinafter”) in the reduced pressure. FIG. 6C is a schematic sectional view showing a flotation of the slider 10 above the disc 2. As illustrated, the slider 10 flies as shown by a solid line in the normal pressure, but drops by about 2.5 nm as shown by a dotted line at an altitude of 3,000 m. Recently, many manufacturers guarantee of 3,000 m use. However, in order to avoid collisions between the slider 10 and the disc 2 due to the drop, the flying height in the normal pressure should be made higher by 2.5 nm. The head 20 suffers recording/reproducing difficulties in inverse proportion to the flying height, and this problem is revealed as degraded yield. For example, when the flying height is set higher by 2.5 nm in the normal pressure, the yield is low of the head 20 that can perform the recording/reproducing operation. The degraded yield results in the increased cost of the HDD.